Method for producing anodized and coated expanded aluminum foil material in a continuous process

ABSTRACT

A method for producing anodized and coated expanded aluminum foil material in a continuous process. The method includes the steps of providing expanded aluminum foil material on a first coil, cleaning the expanded aluminum foil material in a continuous process, anodizing the expanded material in a continuous process after the expanded aluminum foil material has been cleaned, coating the anodized expanded aluminum foil material with an organic coating in a continuous process and winding up the anodized and coated expanded aluminum foil material on second coil.

FIELD OF THE INVENTION

The invention is related to the field of expanded aluminum foil material, and more particularly to a method of producing anodized and coated expanded aluminum foil material in a continuous process.

BACKGROUND

Expanded foil material, such as expanded aluminum foil material, is used in a variety of applications. One such application is for use as lightening strike material for composite materials in aircraft. In the past, manufacturers have relied on the conducting metal skin of aircraft to help dissipate the energy of lightning that happens to strike an aircraft. In general, the metallic skin of an aircraft will help disperse the lightning's energy across a wider surface area which helps prevent excessive damage that may otherwise occur.

Over many years, aircraft designers and manufactures have strived to improve the performance and lower the cost of owning and operating aircraft by increasing the use of composite materials. Indeed, for many years, the leading edges of some aircraft have been formed of composite materials. However, while composite materials can have an excellent strength to weight ratio and other desirable characteristics, they are basically non-conductive and consequently, they do not readily dissipate lightning strike energy. In order to enhance composite material's with lightning dissipative qualities, some manufacturers have adopted the practice of incorporating thin metallic expanded foil materials and metallic screen materials into composite aircraft components. Metal, such as aluminum, has been used since it is lightweight and readily workable and can be incorporated into a variety of contours and shapes. In order to provide for greater resistance to corrosion, the metallic expanded aluminum foil material is typically processed with anticorrosion agents, treatments and/or coatings. These anticorrosion agents and coatings also provide the added benefit of improved bonding adhesion and reduced micro cracking of the structure surface.

The presently used process to manufacture these thin expanded aluminum foil materials comprises starting with an expanded aluminum foil material, such as expanded sheet or foil materials ranging in thickness of (e.g. about 0.0025 to 0.03 centimeters in thickness), cut into sheets, typically about 3.04 meters (10 feet) long and a 1.22 meters (4 feet) wide. These sheets are then batch treated in various baths to clean and anodize the expanded aluminum foil material, and then coat the material. The end results of the processes are individual sheets of anodized and coated expanded aluminum foil material that can be manually incorporated into the composite materials.

The batch treatment process is not ideal since the resulting sheets are fairly small in size, fragile, and in larger structures, such as leading edges of wings, wing panels, fuselage panels, a patchwork of many small sheets of anodized and coated expanded aluminum foil material must be aligned, spliced and arranged during the forming of the composite components. Indeed, given fairly strict requirements for overlapping and/or splicing together sheets of expanded aluminum foil material, a significant additional labor element is required during the lay-up process of forming composite members incorporating lightening strike materials.

There accordingly remains a need for a method of producing anodized and coated expanded aluminum foil material in a continuous process that results in rolls of the anodized and coated expanded aluminum foil material rather than sheets. These rolls of material lend themselves to automated composite lay-up operations.

SUMMARY OF THE INVENTION

The invention provides a method for producing anodized and coated expanded aluminum foil material in a continuous process.

The method for producing coated expanded aluminum foil material in a continuous process, comprising the steps of:

providing expanded aluminum foil material;

cleaning the expanded aluminum foil material in a continuous process;

anodizing the expanded aluminum foil material in a continuous process after the expanded aluminum foil material has been cleaned; and

coating the anodized expanded aluminum foil material in a continuous process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary schematic view of an embodiment of a continuous process of cleaning the expanded aluminum foil material and then anodizing the expanded aluminum foil material in a continuous process.

FIG. 2 is an exemplary schematic view of an embodiment of a continuous process of coating the anodized expanded aluminum foil material with an organic material.

FIG. 3 is a flowchart of an exemplary embodiment of a continuous process of cleaning the expanded aluminum foil material and then anodizing the expanded aluminum foil material in a continuous process.

FIG. 4 is a flowchart of an exemplary embodiment of a continuous process of coating the anodized expanded aluminum foil material with an organic material.

DETAILED DESCRIPTION OF THE INVENTION

Turning to FIG. 1, there is shown an exemplary schematic view showing the process line 10 for cleaning and anodizing the expanded aluminum foil material 12. The process line begins with providing a supply of expanded aluminum foil material 12. As used herein, the term “expanded aluminum foil” includes expanded metal aluminum foils and sheets, wire screens and mesh, and punched sheet material and other such materials in varying thicknesses. As used herein, the term “aluminum”, refers to pure or nearly pure aluminum as well as aluminum alloys. A few examples of aluminum alloys which can use used in the process include alloys known in the aircraft industry such as 1100 series, 3000 series, and 5000 series. The expanded aluminum foil material can conveniently be supplied in a roll or coil 14, which roll 14 is unwound to release the expanded aluminum foil material 12. A front region 16 of the expanded aluminum foil material 12 can be attached to a wind up roll or coil 18 downstream of the process line 10. Alternatively, a section of leader material (not shown) can be attached to the front region of the expanded aluminum foil material 12, and the leader material can be connected to a wind up roll 18 downstream of the process line.

As used herein, the term “anodize” means the formation of a decorative or protective passive film on a metal part by making it the anode of a cell and applying electric current thereto while in an acid such as chromic, sulfuric, phosphoric, or oxalic, etc.

Turning back to FIG. 1, the unwound expanded aluminum foil 12 is first passed through a tank of alkaline liquid 30. The aluminum surface of the expanded aluminum foil material is exposed to the alkaline cleaner for a period sufficient for cleaning of surface contaminants (oil, etc.) Alternative methods of cleaning the expanded aluminum foil material include a degreasing process in which a vapor degreaser, a solvent degreaser is manually used, or an emulsion degreaser is used. In lieu of a cleaning tank within which the expanded aluminum foil material is immersed, alternately a spraying line may be used and the alkaline cleaning agent may be spray or otherwise applied on the expanded aluminum foil material 12 and allowed to dwell on the expanded aluminum foil material to accomplish the cleaning (surface preparation) process.

After passing through the alkaline wash tank 30 (or spraying line), the expanded aluminum foil 12 is next passed through an alkaline rinse tank 32. The alkaline rinse can comprise plain water, or other solutions to thoroughly rinse any remaining alkaline from the surface of the expanded aluminum foil material. The path length and dwell time in each tank are set to achieve the desired results. In lieu of the alkaline rinse tank 32, the expanded aluminum foil material can be sprayed or otherwise be rinsed with a rinse agent instead of being immersed in a tank of rinsing solution.

The rinsed expanded aluminum foil material 12A is passed through a desmut tank 34, where an acid desmut takes place. Smut is a reaction product left on the surface of a metal consisting of various salts or residues of alloy metals such as copper, iron, or manganese after alkaline etching, and should be removed. The acid treatment is used to remove the smut and activate the surface. The inventor has found that nitric acid works well as a desmut agent. The tank 34 can be deep and have a roller 36 to increase the effective dwell time of the mesh in the tank 34, and/or the tank can be made larger. To transition into and out of the desmut tank 34, roller 38 and 40 can be used. As with the other steps, it is possible to use a desmut spraying or application line (not shown) other than an immersion tank of desmut solution.

After being acid desmutted, the acid treated expanded aluminum foil material is passed through a rinse tank 42, which can be filled with a rinsing agent such as clean water. In lieu of the rinse tank 42 within which the expanded aluminum foil material is immersed, alternately, a spraying line may be used and the rinsing agent may be sprayed or otherwise applied on the expanded aluminum foil material 12 to provide for thorough rinsing.

Following rinsing in rinse tank 42, the cleaned and prepared expanded aluminum foil material 12B is ready for anodizing, which takes place by passing the expanded aluminum foil through an anodizing tank 44. In order to increase the dwell time in the tank, a series of rollers 46 are provided, which effectively increases the path length through the bath to provide for adequate residence time for anodizing to take place. The anodizing tank 44 is preferably filled with phosphoric acid for phosphoric acid anodizing.

After passing through the anodizing bath of phosphoric acid, the expanded aluminum foil material is rinsed, either by passing through a rinse tank 50, or by passing through a rinse spray unit (not shown), which rinse solution can comprise clean water or other solutions that remove excess chemicals from the surface of the expanded aluminum foil. The rinsing process should be accomplished within about 2 minutes after the anodization step.

Following rinsing, the anodized expanded aluminum foil material 12C is passed through an oven 52 to dry the expanded aluminum foil material, and then the dried anodized expanded aluminum foil material is passed through a coil wind-up unit 54 which has a series of rollers, after which the anodized expanded aluminum foil material is wound up on the wound up roll 18. A control unit 56 can be used to control all of the various parts of the system.

The continuous anodizing process is unique in that it permits long lengths of web to be treated in a continuous manner. This helps to eliminate excessive numbers of seams in the finished product, is adaptable to automated handling, such as ply cutters and tape laying machines, and provides for lower cost product.

After completion of the anodizing process, the roll or coil of anodized expanded aluminum foil material18 is further processed, e.g. by coating, an exemplary embodiment of which is shown in FIG. 2. Although the coating line is shown as a separate line, it could be directly introduced after the dried anodized expanded aluminum foil material emerges from the drying oven 52.

Turning now to FIG. 2, there is shown an exemplary schematic view of a coating line process schematic 60. In this exemplary schematic view, a roll 18 of anodized expanded aluminum foil material 12C is placed on a coil unwinder unit 66. Downstream of the unwinder unit 66, a coating unit 68, which can consist of a tank or pan of the coating material, can be used to coat the anodized expanded aluminum foil material with whatever coatings are required for the particular application. Other methods to coat materials which exist, such as reverse roll coating, electro-deposition, spraying, etc., can be used.

After passing through the coating unit 68, the coated expanded aluminum foil material is passed through one or more curing/drying ovens 70 and 72, which can consist of conventional convection, infrared, or other heating sources for a time sufficient to cure/dry the coating on the expanded aluminum foil material. The line speed and oven length can be set to achieve sufficient time in the curing/drying oven.

Following the oven curing/drying, the completed coated expanded aluminum foil material 12D is preferably taken up by a take up roll 74 and is ready for use by manufacturers. A control unit 76 can be used to control the coating line process. The coating unit 68, and ovens 70 and 72 can be hooked to venting hoods 78 for processing of any gases and vapors released, e.g., to an emission control device. In order to prevent damage to the thin expanded aluminum foil material, it is important that the process speeds and tensions be sufficient to enable controlled winding of the applied to the expanded aluminum foil material by the coils 14 and 18 and 74, but not so great as to damage the expanded aluminum foil web.

FIG. 3 is a flowchart 90 of an exemplary embodiment of a continuous process of cleaning the expanded aluminum foil material and then anodizing the expanded aluminum foil material in a continuous process. In this process, expanded aluminum foil material is unwound 92, is alkaline exposed 94, and is water rinsed 96. The expanded aluminum foil material is then exposed in nitric acid desmut 100, followed by water rinse 102. Then the expanded aluminum foil material is anodized by passing it through a phosphoric acid bath under electrical charge 104, is water rinsed 106, is dried 108 and is wound up 110. A quality control step 112 may be used to confirm whether the anodized expanded aluminum foil material passes the established standards.

FIG. 4 is a flowchart of an exemplary embodiment of a continuous process of coating the anodized expanded aluminum foil material with a desired coating. Starting with anodized expanded aluminum foil material 12D, there can take place a quality control process 122 to confirm whether the anodized expanded aluminum foil material passes the established standards. Next, another quality control process 128 is carried out to confirm whether the coated expanded aluminum foil material passes the established standards.

Having thus described exemplary embodiments of the present invention, it should be understood by those skilled in the art that the above disclosures are exemplary only and that various other alternatives, adaptations and modifications may be made within the scope of the present invention. The presently disclosed embodiments are to be considered in all respects as illustrative and not restrictive. 

1. A method for producing coated, thin expanded aluminum foil material in a continuous process, comprising the steps of: providing elongate and thin expanded aluminum foil material; cleaning the expanded aluminum foil material in one of a continuous process and a batch form by degreasing the coil roll; and treating the expanded aluminum foil material in a continuous process after the expanded aluminum foil material has been cleaned.
 2. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 1, wherein the step of treating the expanded aluminum foil material in a continuous process after the expanded aluminum foil material has been cleaned comprises the step of anodizing the material in a continuous process.
 3. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 2, wherein the step of anodizing the expanded aluminum foil material comprises passing the cleaned expanded aluminum foil material through a tank of phosphoric acid while electrically charged and rinsing the anodized expanded aluminum foil material.
 4. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 3, further comprising a step of drying the anodized expanded aluminum foil material.
 5. The method for producing coated, thin expanded foil material in a continuous process of claim 4, further comprising a step of winding up the dried anodized expanded aluminum foil material on a coil.
 6. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 1, wherein the step of treating the expanded aluminum foil material in a continuous process after the expanded aluminum foil material has been cleaned comprises the step of applying an organic coating to the cleaned expanded aluminum foil material.
 7. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 2, further comprises a step of applying an organic coating to the anodized expanded aluminum foil material.
 8. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 7, further comprising a step of drying the coated expanded aluminum foil material.
 9. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 8, further comprising a step of winding up the dried, coated expanded aluminum foil material on a coil.
 10. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 1, wherein the cleaning of the continuous expanded aluminum foil material comprises first washing the expanded aluminum foil material in an alkaline solution followed by washing the expanded aluminum foil material in an acidic solution.
 11. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 10, wherein the expanded aluminum foil material is rinsed with water after washing the expanded aluminum foil material in the alkaline solution and the acidic solution.
 12. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 1, wherein the steps of cleaning the expanded aluminum foil material in a continuous process and treating the expanded aluminum foil material in a continuous process take place as the elongate expanded foil material passes through tanks, with uncleaned expanded aluminum foil material being provided on a first coil and the treated expanded aluminum foil material being wind up on a second coil.
 13. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 2, further comprising a step of conducting a quality control check after anodizing the expanded aluminum foil material.
 14. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 7, further comprising a step of conducting a quality control check after the step of coating the anodized expanded aluminum foil material.
 15. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 1, wherein the elongate and thin expanded aluminum foil material comprises aluminum having a thickness of about 0.0025 to 0.03 centimeters.
 16. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 1, wherein the elongate and thin expanded aluminum foil material comprises aluminum expanded aluminum foil material having a thickness of ranging in thickness of about 0.0025 to 0.03 centimeters.
 17. A method for producing coated, thin expanded aluminum foil material in a continuous process, comprising the steps of: providing elongate material; cleaning the expanded aluminum foil material in a continuous or batch process; anodizing the expanded aluminum foil material in a continuous process after the expanded aluminum foil material has been cleaned; and coating the anodized expanded aluminum foil material with an organic anticorrosion coating in a continuous process.
 18. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 17, wherein the step of anodizing the expanded aluminum foil material comprises passing the cleaned expanded aluminum foil material through a tank of phosphoric acid and rinsing the anodized expanded aluminum foil material.
 19. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 18, further comprising a step of drying the anodized expanded aluminum foil material.
 20. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 17, wherein the cleaning of the continuous expanded aluminum foil material comprises first exposing the expanded aluminum foil material in an alkaline solution and rinsing followed by exposing the expanded aluminum foil material in an acidic solution.
 21. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 20, wherein the expanded aluminum foil material is rinsed with water after exposing the expanded aluminum foil material in the alkaline solution and the acidic solution.
 22. The method for producing coated expanded aluminum foil material in a continuous process of claim 17, further comprising a step of conducting a quality control check after at least one of the steps of anodizing the expanded aluminum foil material and coating the anodized expanded aluminum foil material.
 23. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 17, wherein the steps of cleaning and anodizing the expanded aluminum foil material in a continuous process take place as the expanded aluminum foil elongate material pass through tanks.
 24. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 17, wherein the step of coating the expanded aluminum foil material in a continuous process takes place as the expanded aluminum foil material passes through a tank of an organic material.
 25. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 17, wherein the expanded aluminum foil material is provided on a first coil, the anodized expanded aluminum foil material is taken up on a second coil, and the coated expanded aluminum foil material is taken up on another coil.
 26. The method for producing coated, thin expanded aluminum foil material in a continuous process of claim 17, wherein the elongate and thin expanded aluminum foil material comprises aluminum expanded aluminum foil having a thickness of about 0.0025 to 0.03 centimeters.
 27. A method for producing coated, thin aluminum expanded aluminum foil material in a continuous process, comprising the steps of: providing an expanded aluminum foil material having a thickness of about 0.0025 to 0.03 centimeters; cleaning the aluminum expanded aluminum foil material in a continuous process; anodizing the aluminum expanded aluminum foil material in a continuous process after the expanded aluminum foil material has been cleaned; and coating the aluminum anodized expanded aluminum foil material with an organic coating in a continuous process.
 28. The method for producing coated, thin aluminum expanded aluminum foil material in a continuous process of claim 27, wherein the step of anodizing the expanded aluminum foil material comprises passing the cleaned expanded aluminum foil material through a tank of phosphoric acid and rinsing the anodized expanded aluminum foil material.
 29. The method for producing coated, thin aluminum expanded aluminum foil material in a continuous process of claim 27, wherein the cleaning of the continuous expanded aluminum foil material comprises first washing the expanded aluminum foil material in an tank of alkaline solution followed by washing the expanded aluminum foil material in a tank of acidic solution, with water rinses after each step.
 30. The method for producing coated, thin aluminum expanded aluminum foil material in a continuous process of claim 27, further comprising a step of conducting a quality control check after at least one of the steps of anodizing the expanded aluminum foil material and coating the anodized the expanded aluminum foil material.
 31. The method for producing coated, thin aluminum expanded aluminum foil material in a continuous process of claim 27, wherein the steps of cleaning and anodizing the expanded aluminum foil material in a continuous process take place as the expanded aluminum foil material pass through tanks.
 32. The method for producing coated, thin aluminum expanded aluminum foil material in a continuous process of claim 27, wherein the step of coating the expanded aluminum foil material in a continuous process takes place as the elongate, anodized thin aluminum expanded aluminum foil material passes through a tank of an organic material. 